Fan blade assembly

ABSTRACT

A fan blade assembly includes a fan blade body, which has an axle housing downwardly suspending in a center accommodation open chamber thereof at the center and defining therein an axle hole and an inside annular flange in the axle hole, and a core shaft, which is inserted into the axle hole of the axle housing to support magnetic levitation rotation of the fan blade body and has a coupling groove extending around the periphery thereof and coupled to the inside annular flange of the axle housing with a gap left therebetween.

This application claims the priority benefit of Taiwan patent application number 096217239 filed on Oct. 15, 2007.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electric fan and more specifically, to fan blade assembly, which facilitates accurate installation of the core shaft in the fan blade body for enabling the core shaft to support magnetic levitation rotation of the fan blade body stably.

2. Description of the Related Art

Cooling fans are intensively used in different electronic apparatus for quick dissipation of heat energy. When the mechanical operation speed of a cooling fan is increased, the noise level resulted from friction between the core shaft and the axle bearing is relatively increased. Excessive high temperature during operation of a cooling fan may cause burnout of the component parts.

FIG. 1 illustrates a conventional magnetic levitation motor fan. According to this design, a fan blade assembly, referenced by 1, of the magnetic levitation motor fan comprises a fan blade body 11, a core shaft 12, and magnetic devices 13. The fan blade body 11 comprises an accommodation chamber 112, a metal guide plate 113 mounted on the inner surface of the peripheral wall of the accommodation chamber 112, and a plurality of radial blades 111 equiangularly spaced around the periphery. The magnetic devices 13 are mounted on the magnetic guide plate 113. The core shaft 12 is vertically downwardly suspending in the accommodation chamber 112. When the core shaft 12 is coupled to the magnetic levitation motor (not shown), the magnetic devices 13 act with the magnetic levitation motor, causing magnetic levitation rotation of the fan blade assembly 1. This design of magnetic levitation motor fan still has drawbacks. According to this design, the core shaft 12 is made by means of injection molding and fixedly mounted inside the fan blade body 11. During installation of the core shaft 12 in the fan blade body 11, the perpendicularity of the core shaft 12 must be accurately checked. A small deviation of the core shaft 12 will cause unstable rotation of the fan blade assembly 1. The complicated installation procedure of the core shaft 12 greatly increases the consumption of labor and time during fabrication of the magnetic levitation motor fan.

SUMMARY OF THE INVENTION

The present invention has been accomplished under the circumstances in view. It is therefore the main object of the present invention to provide a fan blade assembly, which facilitates accurate installation of the core shaft in the fan blade body for enabling the core shaft to support magnetic levitation rotation of the fan blade body stably.

To achieve this and other objects of the present invention, the fan blade assembly comprises a fan blade body and a core shaft. The fan blade body comprises a center accommodation open chamber and an axle housing downwardly suspending in the center accommodation open chamber at the center. The axle housing has an axle hole axially and downwardly extending to its bottom side, and an inside annular flange transversely extending around the inside wall and suspending in the axle hole. The core shaft is inserted into the axle hole of the axle housing to support rotation of the fan blade body on the core shaft, having a coupling groove extending around the periphery and coupled to the inside annular flange of the axle housing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a conventional magnetic levitation motor fan.

FIG. 2 is a cutaway of a fan blade assembly in accordance with a first embodiment of the present invention.

FIG. 3 is an exploded view of FIG. 2.

FIG. 4 is an enlarged view of a part A of FIG. 2.

FIG. 5 is a schematic sectional side view of the fan blade assembly in accordance with the first embodiment of the present invention.

FIG. 6 corresponds to FIG. 5, showing a magnetic member fastened to the locating hole of the fan blade body.

FIG. 7 is a schematic sectional side view of the fan blade assembly in accordance with a second embodiment of the present invention.

FIG. 8 is a schematic sectional side view of the fan blade assembly in accordance with a third embodiment of the present invention.

FIG. 9 is a schematic sectional side view of the fan blade assembly in accordance with a fourth embodiment of the present invention.

FIG. 10 is a schematic sectional side view of the fan blade assembly in accordance with fifth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 2˜4, a fan blade assembly in accordance with a first embodiment of the present invention is shown comprised of a fan blade body 2 and a core shaft 3.

The fan blade body 2 has an accommodation open chamber 22 disposed at the center and facing one side, namely, the bottom side, a plurality of radial blades 21 equiangularly spaced around the peripheral wall of the accommodation open chamber 22, a metal guide plate 23 mounted on the inner surface of the peripheral wall of the accommodation open chamber 22, a plurality of permanent magnets 24 affixed to the metal guide plate 23, a locating hole 26 located at the center of the top wall of the accommodation open chamber 22 and disposed outside the accommodation open chamber 22 for accommodating a magnetic member 27 (see FIG. 6), and an axle housing 25 downwardly extending from the center of the top wall of the accommodation chamber 22 opposite to the locating hole 26 and suspending inside the accommodation open chamber 22. According to this embodiment, the locating hole 26 is a recessed hole. The axle housing 25 has an axle hole 251 axially and downwardly extending to its bottom side, and an inside annular flange 252 transversely extending around the inside wall and suspending in the axle hole 251. The core shaft 3 is inserted with its one end into the axle hole 251 of the axle housing 25, having a coupling groove 31 extending around the periphery and forced into coupling with the inside annular flange 252 of the axle housing 25.

Referring to FIG. 5, by means of inserting one end of the core shaft 3 into the axle hole 251 of the axle housing 25 to force the coupling groove 31 into coupling with the inside annular flange 252 of the axle housing 25, the installation of the core shaft 3 is quite easy, and a user needs not to worry about alignment between the fan blade body 2 and the core shaft 3. After installation of the core shaft 3 in the axle housing 25, a gap about 0.1 mm exists between the coupling groove 31 and the inside annular flange 252, and the permanent magnets 24 are spaced around the core shaft 3 at a distance.

Referring to FIG. 5 again, when the electric fan is started, the magnetic lines of force of the permanent magnets 24 are separated, and the fan blade body 2 pulled downwards due to the effect of magnetic attraction, keeping the core shaft 3 in position. Because a gap about 0.1 mm exists between the coupling groove 31 and the inside annular flange 252, the fan blade body 2 is supported on the top edge of the core shaft 3 and made to rotate stably in a magnetic levitation rotation manner. During magnetic levitation rotation of the fan blade body 2, the axle housing 25 does not touch the core shaft 3, therefore the friction coefficient between the fan blade body 2 and the core shaft 3 is minimized.

Referring to FIG. 6, after installation of the magnetic member 27 in the locating hole 26 of the fan blade body 2, the magnetic member 27 imparts a magnetically attractive force to the core shaft 3 to secure the core shaft 3 to the inside of the axle hole 251. At this time, the core shaft 3 has its top edge stopped against the center of the top wall of the accommodation open chamber 22 and is kept suspending in the axle hole 251 without touching the peripheral wall of the axle housing 25. Therefore, the fan blade body 2 can be rotated stably in a magnetic levitation rotation manner, lowering friction and noise level.

FIG. 7 is a schematic sectional side view of the fan blade assembly in accordance with a second embodiment of the present invention. This second embodiment is substantially similar to the aforesaid first embodiment with the exception that the locating hole 26 of this second embodiment is a through hole disposed in axial connection with the axle hole 251, and the top edge of the core shaft 3 is directly stopped against the magnetic member 27, enhancing the positioning accuracy.

FIG. 8 is a schematic sectional side view of the fan blade assembly in accordance with a third embodiment of the present invention. This third embodiment is substantially similar to the aforesaid first embodiment with the exception that the locating hole 26 of this third embodiment is a through hole disposed in axial connection with the axle hole 251, and the top end of the core shaft 3 is inserted into the axle hole 251 and the locating hole 26 and secured in place by a retainer ring 28 that is mounted inside the locating hole 26.

FIG. 9 is a schematic sectional side view of the fan blade assembly in accordance with a fourth embodiment of the present invention. This fourth embodiment is substantially similar to the aforesaid first embodiment with the exception that the axle housing 25 according to this fourth embodiment comprises an axially extending axle hole 251, an annular stop flange 29 suspending at the bottom side of the axially extending axle hole 251, an axle bearing 32 mounted in the axle hole 251, and a retaining ring 28 mounted in the axially extending axle hole 251 and stopped between the axle bearing 32 and the annular stop flange 29 and fastened to the coupling groove 31 of the core shaft 3 to secure the top end of the core shaft 3 to the inside of the axle bearing 32; the locating hole 26 according to this fourth embodiment is a through hole disposed in axial connection with the axle hole 251 and holding a magnetic member 27 in direct contact with the top edge of the core shaft 3. According to this fourth embodiment, the axle bearing 32 is a slide bearing.

FIG. 10 is a schematic sectional side view of the fan blade assembly in accordance with fifth embodiment of the present invention. This fifth embodiment is substantially similar to the aforesaid fourth embodiment with the exception that the axle bearing 32 according to this fifth embodiment is a ball bearing.

Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims. 

1. A fan blade assembly comprising: a fan blade body, said fan blade body comprising a center accommodation open chamber and an axle housing downwardly suspending in said center accommodation open chamber at the center, said axle housing having an axle hole axially and downwardly extending to a bottom side thereof and an inside annular flange transversely extending around an inside wall and suspending in said axle hole; and a core shaft inserted into said axle hole of said axle housing to support rotation of said fan blade body on said core shaft, said core shaft having a coupling groove extending around the periphery thereof and coupled to said inside annular flange of said axle housing.
 2. The fan blade assembly as claimed in claim 1, wherein said fan blade body comprises a locating hole on an outside wall thereof in axial alignment with said axle hole of said axle housing, and a magnetic member mounted in said locating hole to attract said core shaft.
 3. The fan blade assembly as claimed in claim 1, wherein said coupling groove is coupled to said inside annular flange with a gap about 0.1 mm left therebetween.
 4. A fan blade assembly comprising: a fan blade body, said fan blade body comprising a center accommodation open chamber, an axle housing downwardly suspending in said center accommodation open chamber at the center, said axle housing having an axle hole axially and downwardly extending to a bottom side thereof and an annular stop flange at the bottom side within said axle hole; an axle bearing mounted in said axle hole inside said axle housing; a core shaft inserted through said axle bearing in said axle hole of said axle housing of said fan blade body to support rotation of said fan blade body on said core shaft, said core shaft having a coupling groove extending around the periphery thereof; and a retainer ring mounted in said axle hole inside said axle housing between said annular stop flange of said axle housing and said axle bearing and coupled to said coupling groove of said core shaft to secure said core shaft to said axle housing.
 5. The fan blade assembly as claimed in claim 4, wherein said retainer ring is coupled to said coupling groove with a gap about 0.1 mm left therebetween.
 6. The fan blade assembly as claimed in claim 4, wherein said axle bearing is a slide bearing.
 7. The fan blade assembly as claimed in claim 4, wherein said axle bearing is a ball bearing.
 8. The fan blade assembly as claimed in claim 4, wherein said fan blade body comprises a locating hole extending through a top wall of said center accommodation open chamber and axially connected to said axle hole of said axle housing, and a magnetic member mounted in said locating hole and stopped against said core shaft. 